This has come up before but....
While we need more NEW aircraft to fill in many gaps (German bombers, Allied tanks, Russia, Italy and Japan in general) there's a couple gaps within the existing plane set that are glaring as well.
I am NOT listing new planes here. I'm strictly listing gaps in the variant lineup of existing planes. Most of you will think "Well so what?" However all of these would be invaluable to scenarios, snapshots, special events and FSO. In some cases variants that are ill-suited to the situation are being substituted because there's nothing else available. I'm also NOT saying that additional variants of already existing aircraft are more important than filling in other glaring gaps in the plane set (He-111, pretty much anything from Japan, etc). However there ARE holes that especially in the SEA would be welcomed with open arms.
Fw-190A3/4 -- Our A5 is really not quite adequate for substituting in many early war situations.
Ju-88 -- Our 88 is an earlier ship. There's a number of later variants, including several fighter/bomber-killers (Ju-88G, etc) that are missing
Ju-87 -- As has been noted, there's quite a few missing variants of the Stuka, including the cannon-armed tank-buster everyone is pining for.
A6M3 -- It's been asked for. Repeatedly. Right now we go from the early-war A6M2 to the later A6M5. There's no real mid-war Zero variant. By comparison, the Spit, 109, P-38, (the H and J are generally similar enough that the J can substitute) Jug, and F4U are covered all the way from entry into service through the end of the war.
F6F-3 -- The same can be said of the Hellcat. The F6F-5 falls into the same category as the F4U-1A: VERY borderline for the Mid War arena. Additionally, the F6F-5 is inappropriate for scenarios from introduction in 1943 to 1944.
B-17D/E/F -- We have NO B-17 appropriate for a PTO scenario as the B-17G wasn't deployed outside of Europe. The B-17G may be the most representative type, but it leaves the Americans without a heavy bomber for the Early War arena. Additionally, in scenarios there's no B-17 appropriate for the Pacific Theater or periods in Europe up to 1942. Additionally, due to the moratorium by HTC on skinning B-17Fs for our G we're missing a lot of famous skins like Memphis Belle. Besides, how often have the EARLIEST B-17s (C/D, etc) appeared in a sim?
B-24 -- Once again, there's no American heavy bomber for the EWA, and the B-24J--except if assumed to be a PB4Y-1 (B-24D custom modified with a nose turret for the Navy)--is inappropriate for scenario setups (such as the Tunisia campaign c1942 currently running in FSO) earlier than 1943.
Lancaster -- Once again, the Mk.III we have is technically incorrect for anything earlier than Mid-war (I know we have her in EWA in-game, but from what I can find the Mk.III is a 1943 bird at LEAST).
Mosquito -- Where to begin? Our Mosquito is a mid-war fighter variant. We're missing any representation of the bomber variants altogether, and none of the earlier or later models of the fighter model.
Seafire -- The rare exception to the Spit lineup. We're missing both the initial Mk.I, and the Mk.III (ironically the first "true" navalized Spitfire variant) and later models.
P-51 -- Ok. We could PROBABLY use the P-51A/A-36. I don't like the thought of Runstangs with 20mm cannon any more than the rest of you, but there is a small gap at the beginning of the P-51's service that the superior high-altitude performance of B/C we have is inappropriate for replacing the Allison Pony.
P-40 -- We're seriously lacking the later end of the P-40 lineup. I won't be able to convince ANYBODY the P-40N would be a valuable addition to the stable in the Mains, but the P-40E is just not appropriate for some of the later PTO setups, (1943ish and beyond) where these later Warhawks figured prominently.
M4 Sherman -- Allied tankers are excited to finally have a white star painted on their turrets. Unfortunately the Sherman Firefly isn't even exactly representative. A number of variants, both early models and later developments like the Easy 8 would be very welcome to fill in the Western Allied tank sets.
Tanks in general -- Really, there could stand to be more earlier or later variants of ANY of the tanks in the lineup.
I'm sure there's others that you all can help me with. But when you get right down to it, there's a SURPRISING number of rather significant holes in the variants of our existing set.